The present invention relates to a hydraulically-operated stripping device used for stripping sheet material to form manholes, or the like, and particularly to the hydraulic operation of the stripping jaws.
A hydraulically operated accident rescue device having spreading jaw means is known from German Patent 26 21 249 of the inventor (assignee) hereof. Various tools can be installed on the tips of the spreading jaws so that, when those jaws are a clamping jaw and a stripping jaw, the accident rescue device can also be used for creating a manhole in a crashed vehicle to afford the rescue team access into the vehicle. The applicant's publication HR 411 65/3D/E5 entitled "Lukas Rescue Systems" shows in the photo on the bottom right of the last page the use of a spreader which is provided with a clamping jaw and a stripping jaw as a stripping device for creating a manhole. The clamping and stripping jaws are shown, for instance, on page 3 of the brochure and their use is described on page 15 in Items 509/510. These rescue devices have proven themselves many times in practice.
Disadvantages are found in the prior designs. Some use jaws placed on arms that are movable relative to each other. Due to the kinematics of some known spreaders, the smallest spreading force is available at the beginning of the stripping process, although the maximum force is required especially at that time in order to cause the sheet metal to tear. The closed arms of the spreader, which are provided with the clamping jaw and the stripping jaw, are in this case inserted into a small hole which has previously been created. The cylinder is then placed under pressure and while the clamping jaw remains stationary, the arm bearing the stripping jaw spreads to peel a strip of sheet metal from the wall of the vehicle.